Prepare

Place the potatoes in a large pot. Fill it with enough water to completely submerge the potatoes by an inch or two. Turn the heat to high and bring the water to a boil. Once boiling, cook the potatoes for at least 15 minutes or until tender enough that the potatoes can easily be pierced with a knife. Drain to potatoes and place them into an ice water bath to cool. Once cool, peel the potatoes—the skin should easily peel away.

Preheat the oven to 425°F. Place the whole, peeled potatoes into a stand mixer, fitted with a paddle attachment. Mix the potatoes on a low speed until smooth. Add the mascarpone, maple syrup, brown sugar, 1/2 of the lemon zest, 1/2 teaspoon cinnamon and the salt. Pour the mixture into the pie shell then place the pie onto a cookie sheet. Bake the pie for 15 minutes and then lower the heat to 350°F and cook for an additional 45 minutes. Remove the pie and let cool.

Pour the cream into the bowl of a stand mixer fitted with the whisk attachment. Whip the cream until soft peaks start to form. Add in the marshmallow fluff and mix on high until the cream begins to stiffen and the marshmallow creme is incorporated. Add in the remaining 1/2 teaspoon cinnamon and lemon zest. Mix until just combined. Spread the marshmallow whipped cream over top of the pie and serve. The pie can be made up to 2 days ahead of time.